Quantitative MRI Study On Cerebral Blood Flow After Carotid Artery Stenting And Endarterectomy

Part? Longitudinal assessment of cerebral blood flow changes following carotid artery stenting and endarterectomyPurpose:Carotid artery stenting(CAS)and endarterectomy(CEA)are major treatment strategy for patients with ICA(internal carotid artery)stenosis,however,the dynamic cerebral blood flow(CBF)changes after CAS and CEA remain unclear.This study aimed to monitor consecutive CBF changes at 24-h intervals in patients who underwent CAS and CEA to explore the potential pattern of CBF alternation and compare the effect on CBF changes of different surgical methods.Materials and Methods:Thirty-two patients(28 males and 4 females;age=63.017.3 years)with 70%-99%ipsilateral stenosis in the ICA were enrolled,of which 19 underwent CAS and 13 underwent CEA by prospective cross-sectional study.Routine head MRI and three-dimensional pseudo-continuous arterial spin labeling(3D pCASL)were performed using a 3.0T system within 7 days prior to operations,and at 4 consecutive time-points(24,48,72,and 96 h)after operations.A volumetric ICA territory,based on gray matter mask according to previous studies,was extracted to measure mean CBF values of ipsilateral and contralateral sides.Comparisons within groups were made using paired Mest and comparisons between groups were made using independent-sample Mest.Results:The CBF values markedly increased at 24 h after CAS and CEA(P<0.05)compared with baseline.Most patients showed peak CBF values on the ipsilateral side at 72 h(13/19,68%)after CAS and at 48 h(10/13,77%)after CEA,then declined.The CBF values for the ipsilateral ICA territory of CEA group were higher than those of CAS group at 24,48,72,and 96 h(P<0.05).Conclusions:The pattern of dynamic CBF changes are different after CAS and CEA,which may be helpful for the improvement of the patient' s postoperative management.Part ? Predicting elevated CBF following carotid artery stenting and endarterectomyPurpose:The purpose of this study was to predict elevated cerebral blood flow(CBF)using three-dimensional pseudo continuous arterial spin labeling(3D-pCASL)by leptomenigeal collateral and antegrade flow in patients who underwent carotid artery stenting(CAS)and endarterectomy(CEA),in the hope of providing a prognosis index for elevated CBF after CAS and CEA and thus to provide some references for the selection of surgical methods.Methods:Symptomatic eighteen patients[15 males and 3 females,age=(61.6±8.2)years]with 70%-99%unilateral internal carotid artery(ICA)stenosis were consecutively enrolled,of these,11 underwent CAS and 7 underwent CEA in a prospective cross-sectional study from November 2015 to February 2017.Routine MRI examinations and 3D-pCASL were performed using a 3.0 T system within 7 days prior to operations,and at 4 consecutive time-points(24,48,72,and 96 h)after the operations.A volumetric ICA territory,based on gray matter mask according to previous studies,was extracted to measure mean CBF values of ipsilateral and contralateral sides.A volumetric internal carotid artery territory based on gray matter mask according to previous work was used to measure mean CBF value of ipsilateral and contralateral side.Collateral flow was calculated using a previously reported method,and was defined as[CBF2.5 s-CBF1.5 s]on the lesion side-[CBF2.5 s-CBF1.5 s]on the normal side,and antegrade flow was defined as CBF1.5 s on the lesion side.Elevated CBF values on the lesion side were defined as(highest CBF2.0 s 24-96 h postoperatively)-(preoperative CBF2.0 s).Pearson's correlation for the relationships between elevated flow,antegrade flow,and collateral flow was determined.Meanwhile,two independent samples t-test was used to compare antegrade flow,collateral flow and elevated flow between patients treated with CEA and CAS.P<0.05 was considered statistically significant.Results:Collateral flow showed a significant positive correlation with elevated CBF(r=0.877,P=0.000)after CAS,but no correlation with elevated CBF after CEA(r=-0.099,P=0.833),despite CEA had higher collateral flow than CAS(P<0.05).Antegrade flow showed a significant negative correlation with elevated CBF(r=-0.905,P=0.005)after CEA,while no correlation with elevated CBF after CAS(r=-0.317,P=0.342),when the antegrade flow is largely identical(P>0.05).Conclusions:Leptomenigeal collateral and antegrade flow effecting on the elevated CBF are different after CAS and CEA:The elevated CBF have significant correlation to the collateral blood flow after CAS and to the antegrade blood flow after CEA,which may provide some references for the selection of surgical methods.